When Kevin Oldt crashed his snowmobile in January 2001, his doctors told him that his spinal cord injury meant he’d never walk again. He was devastated. So it’s with great satisfaction that he tells me his personal record for walking with the help of a robotic exoskeleton from Ekso Bionics: about 5,000 steps in one day.

He clocked those steps in a Dallas convention hall where he spent 4 hours on the show floor demonstrating the features of the Ekso GT, the company’s current commercial model. “And I didn’t feel tired,” he says. “I felt great.”

Oldt recently gave IEEE Spectrum a personal demo at a New York City hotel [video below], accompanied by Ekso CEO Tom Looby and an Ekso physical therapist. While the Ekso GT’s hardware hasn’t changed since it launched in 2014, they were doing a media tour to show how its evolving software has broadened its scope. Thanks to its “variable assist” software, the Ekso GT is the first exoskeleton cleared for use by stroke patients in the United States. It won that FDA approval last April.

The Ekso GT, like the handful of other robotic exoskeletons on the market, is essentially a pair of powered robotic legs. Oldt turns himself into a cyborg by placing his feet on the footplates and securing straps around his legs, hips, and torso. The exoskeleton transfers his weight to the ground, and he uses two arm braces to keep himself from falling over. Walking is a collaborative process: When Oldt shifts his weight to the left, he triggers the robotic leg on the right to take a step forward. Then he shifts his weight to the right for the next step, resulting in a slow but surprisingly natural gait.

The variable assist software comes into play for both spinal cord injury and stroke patients. The physical therapist can reduce the amount of power the Ekso is sending to the robotic legs if the user’s muscles are capable of doing some of the work. And, in a crucial feature for stroke rehab, the therapist can also set different power levels for each leg. That feature is useful for stroke patients who experience paralysis on just one side of their bodies.

The software draws data from dozens of sensors in the Ekso’s frame and motors, which track how much power is being supplied by the robot for each step, and how much (if any) by the user’s muscles. The Ekso displays this info for the therapist, who can use it to adjust levels and push the user to work harder. For patients with incomplete spinal cord injuries, like Oldt, that workout strengthens and repairs neural connections between the brain and the dormant muscles.

Oldt explains that when he first tried out an Ekso in 2011, he used the earlier model that didn’t have variable assist technology. He has described that tryout as a “blindfolded roller coaster ride” where he strapped himself in and let the machine do its thing. (Spectrum wrote about that early Ekso in 2011 when it was just hitting the clinic and doctors still wondered whether it would work.)

With the Ekso GT, Oldt says, he has taken a more active role. In his first year of working with it, his physical therapist noticed that the motors were supplying less power to Oldt’s right leg as he regained some strength there. Gradually the therapist began dialing down power to that leg, essentially dialing up his muscles. Now Oldt watches the numbers and takes pride in providing a higher percentage of the power. “It’s like a video game,” he says. “All I want to do is beat the machine.”

But Ekso CEO Tom Looby says the company’s business strategy is to address the widest patient population possible, and “every patient has to go through the clinic.” He estimates that the 200 Eksos already sold to U.S. and European clinics represent less than 1 percent of the rehab market. The Ekso GT sells for about US $120,000, and the rehab clinic also buys a service package.

The company will build its brand in the clinic, Looby says, while its R&D department continues to work on gear that the user can bring home. Ekso may also develop gear that could help the elderly and all sorts of people with mobility problems. “It won’t be a one-size-fits-all technology,” says Looby.

For Oldt, leaving the Ekso behind at the end of a rehab session isn’t great: “It’s back to the wheelchair, back to reality,” he says. Until the next convention, when he can try to hit 6,000 steps.